Differential antennal sensitivities of the generalist butterflies Papilio glaucus and P. canadensis to host plant and non-host plant extracts (original) (raw)

It is likely that olfaction is used by some generalist insect species as a pre-alighting cue to ameliorate the costs of foraging for suitable hosts. In which case, significantly higher antennal sensitivity would be expected to the volatiles of preferred over less or non-preferred host plants. To test this hypothesis, antennal sensitivity was measured by recording electroantennogram (EAG) responses from intact antennae of the generalists Papilio glaucus L. and P. canadensis R & J (Papilionidae) to methanolic leaf extracts of primary, secondary, and non-host plants. EAGs recorded from antennae of P. glaucus were approximately four fold higher than those of P. canadensis in response to extracts of its most suitable host plant, Liriodendron tulipifera (Magnoliaceae). Likewise, EAG responses of P. canandensis to its preferred host, Populus tremuloides (Salicaceae), were significantly higher than those of P. glaucus. In addition, P. glaucus exhibited significantly higher (approximately three fold) EAG responses to its preferred host, L. tulipifera, than to its less-preferred hosts, Ptelea trifoliata, Sassafras albidum, and Lindera benzoin. The results from this study indicate a significant divergence in the olfactory system of two closely related generalist butterfly species, including a strong specialization in the olfactory system of P. glaucus.